return to home page Computational Chemistry Comparison and Benchmark DataBase Release 22 (May 2022) Standard Reference Database 101 National Institute of Standards and Technology
You are here: Experimental > One molecule all properties

Experimental data for H2 (Hydrogen diatomic)

22 02 02 11 45
Other names
Hydrogen; Molecular hydrogen; o-Hydrogen; p-Hydrogen; dihydrogen;
INChI INChIKey SMILES IUPAC name
InChI=1S/H2/h1H UFHFLCQGNIYNRP-UHFFFAOYSA-N [H][H] dihydrogen
State Conformation
1Σg D*H
Enthalpy of formation (Hfg), Entropy, Integrated heat capacity (0 K to 298.15 K) (HH), Heat Capacity (Cp)
Property Value Uncertainty units Reference Comment
Hfg(298.15K) enthalpy of formation 0.00 0.00 kJ mol-1 CODATA
Hfg(0K) enthalpy of formation 0.00 0.00 kJ mol-1 CODATA
Entropy (298.15K) entropy 130.68 0.00 J K-1 mol-1 CODATA
Integrated Heat Capacity (0 to 298.15K) integrated heat capacity 8.47 0.00 kJ mol-1 CODATA
Heat Capacity (298.15K) heat capacity 28.84   J K-1 mol-1 CODATA
Information can also be found for this species in the NIST Chemistry Webbook
Vibrational levels (cm-1) vibrations
Mode Number Symmetry Frequency Intensity Comment Description
Fundamental(cm-1) Harmonic(cm-1) Reference (km mol-1) unc. Reference
1 Σg 4161 4401 1979HUB/HER      

Detailed diatomic data
ωe ωexe ωeye Be αe ZPE reference
4401.213 121.336 0.8129 60.853 3.0622 2179.307 2007Iri:389

vibrational zero-point energy: 2080.6 cm-1 (from fundamental vibrations)
Calculated vibrational frequencies for H2 (Hydrogen diatomic).
Rotational Constants (cm-1) rotational constants
See section I.F.4 to change rotational constant units
A B C reference comment
  60.85300   1979HUB/HER

Calculated rotational constants for H2 (Hydrogen diatomic).
Product of moments of inertia moments of inertia
0.2770222amu Å2   4.600183E-41gm cm2
Geometric Data
picture of Hydrogen diatomic

Point Group D∞h


Internal coordinates
distances (r) in Å, angles (a) in degrees, dihedrals (d) in degrees
Description Value unc. Connectivity Reference Comment
Atom 1 Atom 2 Atom 3 Atom 4
rHH 0.741   1 2 1979HUB/HER re

Cartesians
Atom x (Å) y (Å) z (Å)
H1 0.0000 0.0000 0.0000
H2 0.0000 0.0000 0.7414

Atom - Atom Distances bond lengths
Distances in Å
  H1 H2
H1   0.7414
H2 0.7414  

Calculated geometries for H2 (Hydrogen diatomic).

Bond descriptions


Examples: C-C single bond, C=C, double bond, C#C triple bond, C:C aromatic bond
Bond Type Count
H-H 1

Connectivity
Atom 1 Atom 2
H1 H2
Electronic energy levels (cm-1)
Energy (cm-1) Degeneracy reference description
0 1 1979HUB/HER 1Σg
91700 1 1979HUB/HER

Ionization Energies (eV)
Ionization Energy I.E. unc. vertical I.E. v.I.E. unc. reference
15.426 0.000     webbook

Proton Affinity (kJ mol-1)
Proton Affinity unc. Product reference comment
422.3   H3+ webbook  
Dipole, Quadrupole and Polarizability
Electric dipole moment dipole
State Config State description Conf description Exp. min. Dipole (Debye) Reference comment Point Group Components
x y z total dipole quadrupole
1 1 1Σg D∞h True 0.000 0.000 0.000 0.000 NSRDS-NBS10   D∞h 0 1
Experimental dipole measurement abbreviations: MW microwave; DT Dielectric with Temperature variation; DR Indirect (usually an upper limit); MB Molecular beam
Calculated electric dipole moments for H2 (Hydrogen diatomic).
Electric quadrupole moment quadrupole
State Config State description Conf description Exp. min. Quadrupole (D Å) Reference comment Point Group Components
xx yy zz dipole quadrupole
1 1 1Σg D∞h True -0.260 -0.260 0.520 1963Orc:605 D∞h 0 1

Calculated electric quadrupole moments for H2 (Hydrogen diatomic).
Electric dipole polarizability (Å3) polarizability
alpha unc. Reference
0.787   1997Oln/Can:59

Calculated electric dipole polarizability for H2 (Hydrogen diatomic).

References
By selecting the following links, you may be leaving NIST webspace. We have provided these links to other web sites because they may have information that would be of interest to you. No inferences should be drawn on account of other sites being referenced, or not, from this page. There may be other web sites that are more appropriate for your purpose. NIST does not necessarily endorse the views expressed, or concur with the facts presented on these sites. Further, NIST does not endorse any commercial products that may be mentioned on these sites. Please address comments about this page to cccbdb@nist.gov.
squib reference DOI
1963Orc:605 RH Orcutt "Influence of Molecular Quadrupole Moments on the Second Virial Coefficient" J. Chem. Phys. 39(3), 605, 1963 10.1063/1.1734300
1979HUB/HER Huber, K.P.; Herzberg, G., Molecular Spectra and Molecular Structure. IV. Constants of Diatomic Molecules, Van Nostrand Reinhold Co., 1979 10.1007/978-1-4757-0961-2
1997Oln/Can:59 TN Olney, NM Cann, G Cooper, CE Brion, Absolute scale determination for photoabsorption spectra and the calculation of molecular properties using dipole sum-rules, Chem. Phys. 223 (1997) 59-98 10.1016/S0301-0104(97)00145-6
2007Iri:389 KK Irikura "Experimental Vibrational Zero-Point Energies: Diatomic Molecules" J. Phys. Chem. Ref. Data 36(2), 389, 2007 10.1063/1.2436891
CODATA Cox, J.D.; Wagman, D.D.; Medvedev, V.A.CODATA Key Values for Thermodynamics. Hemisphere, New York, 1989 10.1002/bbpc.19900940121
NSRDS-NBS10 R. D. Nelson Jr., D. R. Lide, A. A. Maryott "Selected Values of electric dipole moments for molecules in the gas phase" NSRDS-NBS10, 1967 10.6028/NBS.NSRDS.10
webbook NIST Chemistry Webbook (http://webbook.nist.gov/chemistry) 10.18434/T4D303

Got a better number? Please email us at cccbdb@nist.gov


Browse
PreviousNext